Method, mould, device and apparatus for processing roundfish

ABSTRACT

Frozen roundfish, such as codlike white fish, salmon or trout, having a substantially straight shape is longitudinally split centrally of the fish so that the main portion of the vertebral column is removed, and each of the frozen fish halves are subsequently cleaned and searched for impurities, following which the still frozen fish pieces are portion-packed and freeze-stored. With the view of positioning the fish during the splitting it may be frozen in a faceted shape or with raised fins. When the whole, frozen fish body has been positioned with its vertical plane of symmetry in a well-known position, the fish may be securely held by means of fixing means (59) having a part (68) consisting of a fluidum absorbing and flexible material that may be locked in abutment on the exterior of the frozen fish and freeze firmly thereto. The grip of the fixing means in the fish is so strong that it will not be broken by the splitting of the fish.

The invention relates to a method of processing roundfish having anindividual weight as caught averaging from 0.3 to 10 kilos, for portionpacked frozen pieces of fish, where the fish after catch is frozenonboard the fishing boat.

Roundfish are to be interpreted for instance as codfish, Atlanticcatfish, coalfish, haddock, whiting, hake, molusus, macherel, hokai,pollock, salmon, sea trout, redfish and wolffish. Such fish constitutethe major quantity of fish caught with a view to sale as consumer fish.

The large sale volume and consumption of consumer fish are to be foundon the continental markets in Europe, U.S.A. and Asia, i.e.geographically remote from the sea areas where the major quantity ofconsumer fish are caught, entailing that a large part of the sale onsaid markets takes place in the form of frozen, portion packed fish.

The quality of consumer fish is extremely dependent on the manner ofstoring and the time elapsing from the catch. Iced fish generallypreserves a fine quality for two to three days after catch, but after 12to 14 days iced fish are no longer usable as consumer fish. If the fishis frozen within the first 24 hours after catch a high quality maynormally be preserved for several months.

The fishing for codlike consumer fish is presently divided into threemain groups:

A) Coastal fishing where small and large fishing boats land the fish thesame day as caught with the view of selling the fish as high qualityfresh food in the region of landing the catch.

B) The local/regional high sea fishing where medium-sized and largefishing boats remain on the fishing ground until the vessel isfull-loaded or the limit of keeping the first caught fish has beenattained. Due to the extensive fishing period the landed fish will be atleast from 1 to 12 days old. The catch is sold for fresh foodconsumption or for processing in the landbased fish industry.

The fish industry located in the proximity of the continental marketshas difficulty in procuring sufficient supply of high-quality fishbecause the freshest part of the high-sea catch is distributed by coldstorage car on the continental market where the fish is sold as freshfood. This fish industry therefore only disposes of either iced fishthat is from 6 to 12 days old and therefore is of a medium to lowquality, or of fish frozen on sea and thawn, processed into a finishedproduct and refrozen in factory. However, the quality of the finishedproduct suffers from the circumstance that the fish is frozen twice withan intermediary thawing, meaning that the continental fish industry hasdifficulty in competing as to product quality with the industry e.g. inthe Faroe Islands, in Iceland or in Northern Norway, the fish industryhaving there free access to fresh fish because the demand on theconsumer market for fresh fish is there substantially smaller than thelanded quantity of fish.

C) The more distant high-sea fishery where big factory ships catch thefish which immediately after the catch is processed into a commodity inthe form of portion packed fish pieces and is frozen onboard a vesselwhich results in a finished product of a very high quality, saleable atprices that are from 20% to 25% higher than a corresponding frozenproduct processed from fish that are a little older or thawn andrefrozen. The flexibility of the factory vessels is, however, very poor,since the space, movement and weight conditions onboard necessitate verysimple processing lines requiring setting for a specific species of fishand also a specifically approximate size of fish. The failingflexibility entails that all the part of the catch which does notcorrespond to the settings of the processing line is thrown overboard.In view of the fact that the cooling capacity as well as the number ofthe crew are limited the miscut and damaged fish together with lessvaluable parts of the fish are thrown overboard again. On factory shipsit is not unusual that the yield of the finished product corresponds to10 to 15% by weight of the catch.

Quite apart from the problem involved for the continental fish industry,and mentioned under item B), in procuring sufficiently fresh rawmaterials, the fish industry generally suffers from three well knownproblems. Firstly, the utilization of the capacity is low because theindustry in order to uphold the quality of the finished product, has toprocess the fish immediately after it has been landed, and since thefishery is dependent on weather, wind and season and on catch quotafixed by law, there are considerable variations in the landed quantitiesand species of fish and thus in the load of work in industry. Secondly,the fish resources in seas are limited which is inter alia reflected bythe catch quota and, thirdly, the working conditions in fish industryare stressing because the processing is effected as a wet process with avast consumption of water and because the operating crew becomephysically worn-down by doing repeating, uniform movements at a rapidpace.

It has been known for many years to process tuna in a frozen condition.Tuna is a very big fish having an individual weight of up to 500 kilosand inter alia due to its size the tuna is handleable in the mechanicalprocessing. Compared to cod fish, the tuna has a very small amount ofbones in relation to the amount of meat, thereby making it possible tocut away the bones without having an inacceptably large meat loss. FromU.S. Pat. No. 3,594,191 issued in 1969 it is known to cut out the frozentuna into many slices of equal thickness. Since the slices are definedby two parallel cuts it is possible to effect the further processing bymerely placing the slices on a plane base and routing them through aprocessing station at which the backbone and the blood sidemeat are cutaway, e.g. as shown in U.S. Pat. No. 4,748,724, following which theedible meat is cooked, sliced and canned.

FR-A-2,542,577 deals with a circular saw having a diameter ofapproximately 1 m for dividing a whole frozen tuna into smaller piecesthat are handleable in the following processing of the tuna. The tuna isrouted on a conveyor belt and may for instance be separatedlongitudinally by a cut perpendicular to the vertical plane of symmetryof the fish.

DD-A-217,978 describes an apparatus for intersecting a frozen fish blockby means of water Jets, i.e. a boneless product prepared by block-frozenfillets of fish so that the fish block may be divided into slices whichfor instance form part of ready-prepared dishes.

DD-A-257,009 deals with a roundtable with a centrally positioned robotarm for the control of a water jet cutter head for cutting fresh fishkept firmly to the roundtable by means of vacuum or freezing.

It is the object of the invention to provide a method that eliminatesthe above mentioned problems of the fish industry in the processing ofroundfish and that allows the production of high-quality portion packedfrozen pieces of fish, irrespective of the geographical location of thefish industry and of the variations of the landed amounts of catch. Itis a further purpose to offer a high degree of utilization of the caughtfish.

With this in view the above mentioned method is characterized in thatfrozen fish having a substantially straight shape is longitudinallysplit centrally of the fish and the main portion of the vertebral columnis removed by making at least one cut substantially parallel to thevertical plane of symmetry of the fish, in that the cut face in eitherof the frozen fish halves is searched for localizing impurities such asbone remains, pin bones or black membrane, in that at least part of thelocalized impurities is removed from the frozen fish meat and in thatthe cleaned, frozen pieces of fish are portion packed and freeze-stored.

It is a feature of the invention that the fish may be longitudinallysevered without separating the fish by means of transverse cuts throughthe fish body prior to the splitting, such cuts inevitably diminishingthe size of the ready processed fish pieces and thus result in loss ofedible fish meat. For practical reasons the head is, however, frequentlycut off prior to severing the fish body because the head components maythen be removed by a single cut.

By splitting the frozen roundfish in the above mentioned manner andcleaning the meat determined for consumption of the still frozen fishhalves of unwanted impurities, frozen, boneless fish fillets or fishcuttings, such as pieces of loin, block, center or tail, may be preparedin a frozen ready-product quality corresponding to the ready-productproduced by the factory ships mentioned under item C) where the fish isprocessed in fresh condition prior to freezing, and since the processingis carried out ashore the previously known high percentage of spillageof the catch may be eliminated by processing mainly the whole fish,because the frozen fish may be sorted as to species and size prior tothe processing and the processing equipments may be designed to beextremely flexible.

In view of the fact that the fish is individually frozen onboard thefishing boat irrespective of the species and size of the fish, all catchmay be landed, even in a quality corresponding to the day-fresh fishlanded by the vessels referenced under item A).

The apparatus for freezing whole fish does not require much space and itmay therefore be installed in medium and large sized vessels asmentioned under item B) which land by far the major quantity of theconsumer roundfish. Owing to the freezing the landed fish has a uniform,very fine quality and the fishing boat may further remain on the fishingground until full cargo, because it is no longer needed to go intoharbour before the first caught fish gets too old.

The fish is landed and completely processed in frozen condition, therebyallowing the fish without loss of quality to be conveyed over longerdistances to the fish industry and be stored there prior to thefinishing processing. The fish industry thus obtains, on one hand, freeaccess to purchase raw materials from remote landing places and, on theother hand, the possibility of processing the fish in step with orderscoming in instead of according to the supply of raw material, and itwill further be possible to obtain a uniform and full utilization ofcapacity in the individual factory. The invention also makes it possibleto allow the processing to be effected as a high-automatized processonly requiring a small number of operating persons and being thusappropriate for working in three shifts.

In a preferred further development of the method according to theinvention the amount of consumer meat cut away by splitting the fish hasbeen minimized in that the splitting cut is effected longitudinallythrough the fish in such a manner, that the spinous pegs of thevertebral column are cut away from the fish meat but that a transverselyouter segment of the vertebra segments is left in the frozen fish meatand in that the vertebra segments by the following searching arelocalized in the fish meat and removed therefrom, preferably by milling.The narrow splitting cut ensures that only a small part of the consumermeat is lost which is of great importance for the economy in theprocessing of roundfish containing a comparatively large amount of bonescompared to the amount of meat.

By the freezing of fish onboard the fishing boat it may be taken intoconsideration how the subsequent processing is being carried out, themanner of freezing being decisive of how to position the fish prior toaffecting the splitting cut. Popularly spoken, the manner of freezingand the manner of positioning are mutually correlated in the same way askey and lock.

When the caught fish is frozen with the view of processing according tothe above mentioned method, this may according to the inventionappropriately be effected in that the fish after catch and ventralcleaning are individually held and formed so that the fish has asubstantially straight shape, and that its exterior shows at least twowell-defined plane areas, preferably opposite each other on either sideof the fish and extending across a substantial part of the length of thefish, and that the fish is held in this shape until at least the outerlayer of the fish is frozen. The well-defined plane areas serve to guideand position the fish while being processed so that the vertical planeof symmetry of the fish may be oriented in relation to the incisionproducing cutter means, such as a saw. The plane areas may be providedin that the fish during freezing is kept firmly in a mould having atleast two plane, longitudinal lateral faces with a length correspondingto a considerable portion of the length of the fish body, where thewidth of the lateral faces declines from the one end to the other, andwherein the internal clearance of the mould transversely to the plane,lateral faces is smaller than the anatomically natural width in the samedirection of the fish inserted in the mould. Upon introducing the fishinto the mould its curved lateral faces will be deformed into a planeshape of the plane lateral faces of the mould.

According to an alternative method according to the invention the fishmay be frozen in that it is suspended at the tail after catch andventral cleaning, that the fins of the fish are raised and that the fishis subsequently flushed with coolant, such as brine, until the raisedfins and at least the outer layer of the fish is frozen, following whichthe whole fish is subjected to freezing while maintaining thesubstantially straight shape obtained by the suspension at the tail.

Experiments have shown it expedient to sever the fish by means of a sawwhose cut at least cuts away the spinous pegs of the vertebral column.Prior to laying the cut the saw and the fish must be positioned inrelation to each other so that the saw may bisect longitudinally throughthe fish substantially parallel to its plane of symmetry. The inventiondelineates three different methods of this positioning of the fish.

The first method builds on the recognition that the fins of the fish arepositioned in the desired plane of symmetry. This method is inter aliacharacterized in that at least two fins of the frozen fish are cut awayso that the fin rays positioned in the fish meat occur in the cut, thatthe position of the fin rays is detected and the vertical plane ofsymmetry is determined from the positions of the fin rays.

The second method of positioning the fish is used in connection withfish which during the initial freezing is formed with an exterior havingat least two well-defined plane areas as explained above. In this methodthe plane areas are used to place the fish in a position with a wellknown position of its vertical plane of symmetry.

The third and preferred method is practised in connection with fishfrozen with raised fins as described above. The raised fins are hereused to position the fish in the desired position which may be effectedin a simple manner because the fins are positioned in the plane ofsymmetry.

The invention further relates to a device for use in positioning thefish according to the last mentioned method. The device is characterizedby having a lower part and an upper part having each a longitudinal slotguide opposite each other, said slot guide having a length at least ofthe same size as the fish body and a depth larger than the height of theraised fins, and in that the upper part is movable in relation to thelower part in such a manner that the guide slots in the two parts stillremain substantially in the same plane. The fish may in an extremelysimple manner be positioned within the device by pulling it with thetail in front in between the lower and upper part in such a manner thatthe fins slide as a slide member into the slot guides acting asguideways, thereby entailing that the vertical plane of symmetry of thefish be made to flush with the slot guides opposite each other. Themovability of the upper part in the plane of the guide slot ensures thatthe upper part may be moved away from the lower part in step withpulling the fish in between the two parts.

With the view of facilitating the insertion of the fish into the device,this is appropriately shaped so that the lower part and the slot thereinare considerably longer than the upper part, that each of the slotguides in the lower and upper part discharges into a wedge-shaped infeedopening at one end of the slot guide, and that the underside of theupper part is bevelled at the infeed end. While one fish is beingprocessed another fish may be positioned with the fins in engagementwith the guide slot in the protruding portion of the lower part. Whenthe fish is fed in beneath the upper part, the upwards facing part ofthe narrow tail end of the fish body will meet the bevelled underside ofthe upper part so that the upper part by itself is lifted in step withpulling the fish in between the parts. The wedge-shaped infeed openingsfacilitate the insertion of the fins in the slot guides.

It is important to be able to firmly hold the frozen fish in a secureand precise manner during the splitting proper, the fish beinginfluenced when splitting with a saw both by vibrations and by a forcein the cutting direction of the saw. With the view of obtaining a simpleand safe securing of the fish while being processed, the inventiondiscloses a device being characterized in that it comprises a number offixing means to be locked in abutment on the exterior of the frozenfish, and that the part of each fixing means determined to abut on theexterior of the fish includes an absorbent and flexible material,preferably of a porous synthetic material, such as nylon fiber material,foam rubber or polyurethane foam. Before the fixing means are made toabut on the frozen fish the flexible material is wetted with a liquidwhich upon abutment on the fish will freeze thereto. It has turned outthat with such a device an extremely good fastening of the fish isobtained. When the flexible material is made to abut on the exterior ofthe fish it assumes the shape of its contour so that the seize areabecomes large. It has further turned out that the trip of the materialon the fish is unaffected by vibrations, presumably because thevibrations are absorbed by the flexible material.

A structurally very simple design of this device is characterized inthat it has two holders, each carrying a number, preferably at leastthree, fixing means distributed over a length corresponding to thelength of the fish body, and in that the holders are situated on eitherside of a fish positioning device and are so pivotally journalled thatthe holders are rotatable through an angle of substantially 90° betweena position in which the flexible material of the fixing means may abuton the sides of a fish disposed in the positioning device, and aposition in which the surface of the flexible material determined toabut on the fish body faces upwards. With said design of the holderdevice the fish only needs to be retained in the positioning deviceuntil the holders have been swung up into the position in which each ofthe fixing means seizes a respective side of the fish and retains it.The fish fastened in the holder device may then be routed through thevarious processing steps. After the fish is split the two holders may berotated to their respective side so that the cut face of either fishhalf is made to face upwards. In this position the cut faces are exposedand easily accessible for the following inspection for and cleaning awayof the undesired impurities.

The above mentioned devices and methods may in appropriate combinationsbe put to use in an apparatus for carrying out the method according toclaim 1 or 2, said apparatus being characterized by the features claimedin claim 13. This apparatus makes an automatized processing of the fishpossible and thereby replaces the previously known manual handling whichexerted a physically wearing-down effect on the operating staff. Theprocessing according to the invention further provides for obtaining theimportant advantage that the water consumption of the fish industry andthus the load of waste water are reduced, the processing in theapparatus according to the invention being carried out as a dry process.

Examples of embodiments of the invention will now be described in moredetail with reference to the schemtical drawings, in which

FIGS. 1 and 2 illustrate a mould for use in the faceted freezing offish,

FIG. 3 depicts an apparatus for freezing fish with raised fins,

FIG. 4 is a side elevation of a codfish and showing the position of thebones,

FIG. 5 is a plane view of an apparatus for the processing of frozenfish,

FIG. 6 is a perspective view of a preferred embodiment of a device forthe positioning of fish with raised fins and a device for securelyholding the fish,

FIG. 7 is a simplified plane view of the holder device,

FIG. 8 depicts on a larger scale a perspective view of a fixing meansfrom the holder device,

FIG. 9 a section along the line A--A in FIG. 5,

FIG. 10 is an illustration of a codfish, viewed from above, the dorsalfins being cut away, and

FIG. 11 illustrates a perspevtive view of an apparatus for the facetedfreezing of fish.

The high quality of freshly caught fish may be preserved by freezing thefish immediately after catch. It is an aspect of the invention that thefish is frozen in a substantially straight shape, so that in frozenstate it may be completely processed into portionwise packed frozenpieces of fish. The interpretation of the expression substantiallystraight shape is that the backbone of the fish is in one plane or thatthe backbone only curves so faintly that a saw may lay a cut along thebackbone. As illustrated in FIGS. 2 and 3 the fish may be frozen in astraight shape by being suspended at the tail during the preliminaryfreezing.

It is possible already at the stage of freezing to take intoconsideration how the further processing of the fish is to be effected,in particular how to position the fish with a well known positioning ofits vertical plane of symmetry.

FIG. 1 shows one half of a mould 1 having three inwards facing pairs ofopposite lateral faces 2, 3 and 4 the width of which declines so fromone end to the other end of the mould that this is funnel-shaped with atapering corresponding to the tapering of the fish body from the head tothe tail end. The distance between the edges that are positionedremotest from each other of the lateral faces 2 and 4 corresponds to theheight of the fish whereas the distance between the pair of lateralfaces 3 is a little shorter than the width of the fish. When the fish isinserted in the mould its curved exterior becomes deformed by thelateral faces 2, 3 and 4 so that elongated, plane areas on the fishoccur. As the fish is oval it will by itself be oriented so in the mouldthat the lateral faces 3 are parallel to its vertical plane of symmetry.At its narrow end the mould has an opening 5 allowing passage of thefish tail which, as illustrated in FIG. 2, may be fastened between thejaws of a tail clamp 6 suspended in a conveyor 7 in such a manner thatthe fish suspended at its tail may be passed through a vessel 8 withcoolant, such as NaCl-brine that may have a temperature of -18° C.

The mould 1 is advantageously made from bent thin sheet metal with sucha small wall thickness that the heat from the fish is rapidly drained tothe coolant in vessel 8.

In the embodiment shown in FIG. 2 the length of the mould and of thefish body corresponds by and large to each other. The mould may ofcourse be substantially longer than the fish which allows to use one andthe same mould for many different fish sizes.

The mould may as well be provided with longitudinal slits which allowthe fins of the fish to protrude from the mould so that they do not bythe freezing entail that areas around the fins of the fish body getdeformed.

As an alternative to tail suspension of the fish the mould may becomposed of two halves divided along the longitudinal plane of symmetryof the mould and which may be locked around the fish and capture it. Theexternal side of the mould halves may be secured to pivotal arms guidingand supporting the mould under the seizing movement and the subsequentmovement through a vessel with coolant or suspension in a cold storage.

FIG. 3 is a sketch of an apparatus for freezing the fish with raisedfins. An endless conveyor 9 carries a large number of tail clamps 10 inwhich the fish in an infeed station is seized at the tail. In afollowing station 11 the fins of the fish are raised by means of twopairs of counter-rotating rollers 12 of which only one roller of eitherpair is shown for the sake of clearness. The rollers of each pair arejournalled so that they are spring-biassed for movement towards eachother so that after they have been made to abut on the sides of thefish, they follow the contour of the fish and grasp and raise the finswhen the pairs of rollers are moved in the direction of the arrow 13.The rollers may be vertically oriented but it is preferred, as shown inFIG. 3, that their longitudinal axis is by and large horizontal and thatthe rollers of each pair form an acute angle with each other so that thefins project in the direction towards the angle apex and are brushed toan upright position upon moving the rollers from the tail end of thefish to its head end.

The fins may alternatively be raised in that the conveyor has a pathsection in which the fish are positioned with their longitudinal axisoriented in the horizontal direction and in which the conveyor pulls thefish horizontally forwards simultaneously with the fins projecting intoone or more slots whose side walls are provided with teeth grasping thefins and raising them.

Immediately after raising the fins the conveyor 9 moves the fish inbetween two spraying pipes 14 flushing the fish with coolant, such asNaCl₂ -brine at a temperature of -18° C. The spraying pipes extend inparallel with the conveyor and have a length ensuring that the fins ofthe fish and the outer layer of the body are frozen when the fish haspassed the spraying pipes. When the fish body has been frozen to such adepth that the fish is dimensionally stable even though it is not longersuspended at its tail, the fish may be released from the tail clampwhereafter the further freezing may occur in a refrigerating chamber orin a brine bath.

The frozen fish may then be glazed, landed and conveyed in a frozenstate to a factory for further processing.

In order to facilitate the understanding of the following description ofthe processing of the fish the bone structure in a codlike white fish isillustrated in FIG. 4. The vertebral column 15 (Columna Vertebralis) ispositioned in the vertical plane of symmetry of the fish and includesthe spinous pegs 16 extending from the vertebrae 18 of the spine 17.Ribs (Costae) and pin bones 20 (Epipleuralis) extend from the part ofthe spine positioned adjacent the ventral cavity, said ribs and pinbones extending substantially transversely to the vertical plane ofsymmetry. By the fish processing at least the vertebral column 15 andpossibly also the ribs 19 and the pin bones 20 should be removed fromthe fish meat determined for consumption.

FIG. 5 shows an apparatus in the form of a roundtable 21 for theprocessing of the frozen fish. The roundtable includes the followingconsecutive processing stations:

a first station 22 at which the fish is fed in and fixed in theapparatus, as described below,

a head cutter station 23 at which the head of the fish in a manner notshown is cut off the body,

a second station 24 at which the fish is split longitudinally by layinga cut with a saw through the fish parallel to its vertical plane ofsymmetry,

a third station 25 at which the two fish halves are oriented with thecut facing up,

a fourth station 26 at which a detector in the form of a video camera 27scans the fish meat in order to localize undesired impurities,

a fifth station 28 at which undesired impurities are removed,

a supplementary detector station 29 for rechecking the cleaning,

a further cleaning station 30 at which possible remaining, undesiredimpurities are removed,

a sixth station 31 at which the cleaned fish halves are released fromthe holder device, and

a seventh station 32 at which the holder device is cleaned and madeready to receive the next fish.

The roundtable 21 is provided with a number of holder devices 33corresponding to the number of processing stations. As indicated inFIGS. 5 and 9, the holder devices 33 are rigidly connected with andcarried by a horzontally positioned ring 34 supported by a number ofcarrying wheels 35 running in an upwards facing annular guide groove 36in a frame 37 standing on the floor. The ring 34 may by means of adriving motor, not shown, be rotated indexingly so that the holderdevices are moved through the row of processing stations.

FIG. 6 shows in more detail an example of the design of the firststation 22 which is determined for the infeed of fish frozen with raisedfins. A positioning device comprises a lower part 38, 38' and an upperpart 39 each of which is composed of two upright parallel plates 40 ofsynthetic material mounted in such a spaced relationship that there is aslot guide 41 between them, the width and depth of which are sufficientto receive the frozen fins in the slot. The slot guides 41 in the upperand lower part are positioned in the same vertical plane, therebycausing the vertical plane of symmetry of the fish to be positioned inthis plane when the fish is inserted between the parts with the fins inengagement with the slot guides.

The upper part carries at its end facing towards the center of theroundtable a horizontally extending guide shaft or two guide pins 42Journalled in a pair of vertically extending guide slits 43 provided intwo upright plate members 44 stationarily fixed in relation to the frame37 of the roundtable. The plates 40 of the upper part are fixedlymounted on a flange section having an upright flap 45 to which a pullrod 46 is pivotally secured at a distance from the guide shaft 42. Thepull rod 46 may by means of a pneumatic cylinder 48 be activated to movein the direction of the arrows 47 so that the upper part may be liftedinto an inactive position in which it gets clear of the lower part and afish placed therein, and down into an active position in abutment on thelower part. In the active position of the upper part the pull rod 46 isunloaded, thereby allowing the upper part 39 to be freely pivoted inrelation to the lower part or be displaced away from it by the upwardssliding movement of the pins 42 in slot guide 43.

The plates 40 of the lower part 38 are divided into two sectionsseparated from each other, viz. an internal section 38 stationarilymounted in relation to the holder device 33 and an external section 38'which by means of a number of stiffeners 49 is stationarily mounted inrelation to the frame 37. Due to said bipartition of the lower part, afish may be positioned with the dorsal fins in engagement with the slotguide 41 in section 38' of the lower part during moving of section 38 ofthe lower part away from the cleaning station 32 to the infeed station22. When section 38 has been rotated into position vis-a-vis section 38'and the upper part 39 has been moved down into the active position inabutment on the lower part, the fish is pulled or pushed with the tailin front, in a manner not shown, in between the lower and upper part. Inorder to facilitate the insertion of the fins in the slot guides 41these slot guides are in the radially outwards extending directionprovided with wedge-shaped infeed openings 50, 51 and 52 guiding thefins into the slot guides 41. At the infeed end the underside of theupper part has a bevelled edge 53 sliding against the belly of the fishupon inserting the fish, thereby lifting the upper part as the fishpenetrates between the parts. The infeed of the fish between the parts38, 39 is stopped when the pectoral fins are on a level with the extremeend of the section 38 of the lower part. This may for instance beeffected in that the pectoral fins hit two stops, not shown,stationarily mounted in relation to the section 38. When the fish hasbeen inserted into this position, the holder device 33 is activated forfixing the fish, following which the upper part 39 is lifted into aninactive position and the ring 34 rotates the captured fish to the headcutter station.

In the embodiment illustrated in the drawings one internal lower partsection 38 is disposed at each holder device 33. As the lower part isonly used to position the fish, it is of course possible to design theroundtable with only a single section 38 which at the first station ismounted vertically displaceably between the active position shown inFIG. 6 and an inactive position in which section 38 is moved as muchdownwards as to get clear of the rotating part of the roundtable anddoes not any longer engage the fins of the fish retained in the holderdevice 33.

If the fish is not frozen with raised fins but instead with at least twoplane, well defined areas on its exterior, the positioning may beeffected by a device which by means of guide plates guides the fish intothe desired position. If, for example, the fish is frozen in the mouldillustrated in FIGS. 1 and 2, the positioning device may comprise twohexagonal rings arranged at either end of the holder device 33. Theradially innermost ring may then have a shape corresponding to thesection of the mould 1 marked by 54 in FIG. 2, while the radiallyoutermost ring may have a shape as the mould section marked by 55. Whenthe fish has been inserted in the rings it will be positioned with itsvertical plane of symmetry in a vertical plane. After the holder deviceis activated to capture the fish the two guide rings are removed, e.g.in that each ring is formed in two parts that are moved away from eachother.

It is obviously possible within the scope of the invention to design themould 1 and the positioning device in many different correlative ways.For instance, the mould 1 may have a rhombic cross-section so that thefish during freezing is formed with a wedge-shape along the top side andthe bottom side, and in this case the positioning device may consist ofa lower part and an upper part substantially corresponding to the parts38 and 39, except that the slot guides 41 have a wedge-shapedcross-section with a wedge angle corresponding to the acute anglebetween the rhomb-forming lateral faces of the freezing mould.

If the fish is frozen in a straight condition without further measures,i.e. neither with raised fins nor with plane areas that may serve asguide faces, it is still possible to position the fish in the desiredposition, but in this case a somewhat more complicated positioningdevice is required. In such a positioning device, not shown, acutting-away is at first effected of at least two and preferably of alldorsal and ventral fins by means of a knife or a miller, see the fish inFIG. 10. The fish is then illuminated by a fluorescent light sourcemaking the fin rays in the fish meat to occur as a row of luminous dots56 in the cut 57. Said dots may be detected by means of a video cameraand from the positioning of the dots the vertical plane of symmetry ofthe fish may be determined in a computer, because the fin rays arepositioned in the plane of symmetry. Subsequently, holder and guidemeans may turn the fish into the desired position and the holder devicemay be activated to retain the fish.

The holder device 33 includes a holder 58 provided on either side of thepositioning device and having various, in casu four, fixing means 59which, consecutively positioned in the longitudinal direction of thefish to be captured, are pivotally Journalled in two parallel supports60 that are spaced apart and are secured to and supported between twopivot arms 61, 62, which are so pivotally Journalled in two uprightflanges 63 rigidly connected with the ring 34 that the holder 58 may bepivoted from the position shown in FIG. 6 in which the holder abuts onthe base 64 and a position in which the holder 58 is pivotedapproximately 90° upwards so that the fixing means 59 are directedtowards the side of the frozen fish inserted in the positioning means.

The pivoting of the holder 58 may for instance be effected in that avertical rod (not shown) pivotally secured to the arm 61 islongitudinally displaced in the upwards or downwards extending directionby a driving means disposed beneath the holder.

As appears from FIG. 8, each fixing means is composed of an angular arm65 which at its central, angular bending carries a pivot pin 66 insertedin bores in supports 60. The fixing means carries at its end facingtowards the fish a pad 68 secured to a base 67 and made from a flexible,absorbent material of a porous synthetic material, such as nylon fibermaterial, foam rubber or polyurethane foam. It is also possible to makeuse of a piece of naturally available sponge. When the pad 68 afterbeing wetted or moistened with liquid is brought into contact with thefrozen fish body it conforms firstly to the peripheral shape of the bodyand then firmly freezes to the fish.

Experiments have shown that a pad of the dimensions 30×30×8 mm offers aretaining force of approximately 120N of tension perpendicular to thesurface of the frozen fish. With this pad and similar pads of nylonfiber sponge and foam rubber which were loaded Until the retainment gotdamaged, it turned surprisingly out that the freeze connection betweenthe fish and the pad did not burst but the bursting took place, however,in the pad proper which was torn across.

A torsion spring 69 whose one end is fastened to the arm 65 and whoseother end is fastened to the support 60 urges the fixing means to movetowards the fish body. It appears from FIG. 7, from which the uppersupport for the sake of clearness is removed, that the fixing means arecapable of rotating inwards to abut on the fish, notwithstanding whetherthe exterior of the fish is at a varying distance from the supports 60.A pull rod 70 is positioned in guidances, not shown, on the one support60 and extends past the outer end of arms 65. Next to each arm the pullrod has a projecting driving stud 71 which by the longitudinaldisplacement of the rod in the direction of the arrow 72 may be made toabut on the outer end of the arm 65 and by a further displacement of therod the arms are pivoted in the direction of the arrow 73 in a directionaway from the fish body until the fixing means occupy the retractedposition shown in FIG. 6.

When the fish is to be fixed and the holder 58 has been swung into itsupright position on a level with a fish body, a driving means 74activates the rod for displacement in the opposite direction of thearrow 72, whereby the fixing means are released and swing into abutmenton the fish body. The rod 70 is pushed still a distance forwards,whereby a conical enlargement 75 of the rod consisting of an elasticmaterial is squeezed in under the outer end of each arm 65, therebyfirmly locking the fixing means in position against the fish body.

It should further be observed that the pivot arm 61 is angularly bentand that the arm 62 is straight so that the supports 60 by and largeextend parallel to the exterior of the fish when the holder device isswung up into engagement with the side of the whole fish. After the fishhas been severed and the holder 58 has been pivoted to the positionshown in FIG. 6, the further advantage is obtained by this design of thepivot arms 61, 62 that the upwards facing cut of the fish half will bemainly horizontal.

The processing of the fish will now be described in more detail. Afterthe infeed, the orientation and the fixation of the fish in station 22and the head cut-off in station 23 the holder device 33 with thecaptured complete fish body is routed to station 24 at which a saw 76 ismounted in a slide guide, not shown, which may move the saw in such amanner in the radial direction of the roundtable that the saw blade orthe saw blades passes/pass into slot guide 41 in the lower part 38 ofthe holder device. The stationary part of the roundtable is providedwith a recess 77 making space for the saw during the movement thereoffrom the inactive position located radially outside the roundtable,shown in solid lines in FIG. 5, to the radially innermost activeposition, shown in dot-and-dash lines, in which the saw blade has passedthroughout the length of the slot.

As indicated in the drawings, the saw may comprise two verticallyoperating band saw blades each running over a respective set ofsuperposed driving wheels 78. The two parallel, longitudinal cuts in thefish only have a slight width and the cuts may be so close to each otherthat a transversely outer segment of the neural spines is left in thefrozen fish meat in either of the fish halves. In this manner only asmall portion of the fish meat determined for consumption is removed andthe spinous pegs of the backbone are simultaneously cut away.

The saw may alternatively be a circular saw the blade radius of which islarger than the height of the fish. In order to obtain a cut with asufficient width for cutting away the spinous pegs the teeth of thecircular saw may be set in lateral direction. The necessary cut widthmay also be obtained in that the blade of the circular saw is mounted onthe driving shaft by means of wedge-shaped drunken-saw discs so that theplane of the blade is not completely perpendicular to the longitudinaldirection of the driving shaft.

After the severing, the holder device 33 is rotated to station 25, inwhich the holders 58 are pivoted away from each other until the fishhalf fixed each holder is oriented with the cut face facing upwards.

Now the holder device 33 is moved to station 26 at which the cuts aresearched to localize impurities in the fish meat. In order to facilitatethe identification of the fish halves the fins in FIG. 5 are shown indot-and-dash lines in spite of the fact that they were cut away from thefish halves by the splitting cut.

The cuts are scanned with a video camera to localize impurities in thefish meat. Impurities in the form of black membrane and the like may bedetected as dark areas in the cut. In order to facilitate the localizingof bone remains the cut may be illuminated by a fluorescent light sourcemaking bone remains to brighten in comparison with the surrounding fishmeat. The scanning localizes impurities in relation to the holder device33 which has a well known positioning. The signals emitted by thescanning are transferred via wires 79 to a computer 80 which from thereceived information determines which of the impurities are to beremoved.

When the fish halves are then moved to station 28 the computer operatesas a control unit for cutting means which remove the unwantedimpurities. The cutting means may for instance comprise a miller head 81mounted on x-y guides 82 controlling the miller head in accordance withthe control signals received from the computer 80. The miller heads 81remove at least the residuals of the backbone such as the neural spinesegments which by the severing of the fish may be left in the fish meat.

The stations 29 and 30 are structured in the same way as stations 26 and28 and they serve to re-check the cleaning carried out in station 28. Itis thus ensured that possible impurities that might be revealed by thecleaning in station 28 are found and removed from the fish meat.

The cleaned and re-checked fish halves are then routed to station 31 inwhich the downwards facing exterior of the fish halves is heatedsufficiently to loosening the grasp of the fixing means 58 at the fishsurface. The heating may for example be effected by means of vapour orradiation heat.

The fish halves are then lifted from the holder device 33 in that apivot arm 83, positioned under the roundtable and which at its extremeend carries four rods 84 which extend in the radial direction of thetable and are capable of passing upwards past the holders 58 and abut onthe exterior of each fish half, is swung up into the position shown indot-and-dash lines in FIG. 9, in which the rods 84 have lifted the fishhalves clear of the holder device. In this position the fish halves abuton the underside of a conveyor 86 which at its one end is pivotallysuspended in a holder 87 fixed in relation to the frame 37. When thefish halves abut on the conveyor whose lower-most conveyor belt run 88is moved in the direction towards the center of the roundtable, the fishhalves will be drawn in between a hold-down roller 89 pivotallyjournalled in holder 87 and a skinning means 90, e.g. of the type"Steen" manufactured by the Belgian company F.P.M. International N.V.After skinning the fish halves are disposed on a conveyor belt 91passing the cleaned and skinned but still frozen fish halves on to aportioning and packaging station at which the fish pieces are packaged,possibly after being portioned and divided into special cuttings thatmay be of the type previously described. This cutting-up may forinstance be effected in a known manner by means of water Jet cutting.

In station 32 the holders 58 are pivoted into the raised position andthe driving means 74 is activated to swing the fixing means 59 into theinactive position by means of the pull rod 70 and the driving studs 71.Concurrently herewith the holder device is cleaned by flushing with hotwater or by means of vapour spraying, thereby moistening the pads 68 sothat they are ready to abut on the exterior of the following fish.

The computer 80 may be programmed to control the function of all activeparts of the roundtable.

FIG. 11 illustrates a schematic diagram of an apparatus for facetedfreezing of fish. The apparatus includes many mould units composed of anupper frame carrying a number of juxtaposed moulds of the aforementionedtype.

At one end of the apparatus there is a mould unit 101 to be filled withfish, vis-a-vis and on a lower level than a container 103 containingventrally cleaned fish. As indicated by the arrows 113 a fish is, forexample manually, filled into each mould 102 so that the tail end of thefish faces downwards and its exterior becomes deformed by the mould inthe above mentioned manner. The filled mould unit is moved in thedirection of the arrow 114 under the container 103 and on to a liftingunit 104 which seizes the mould unit and lifts it above and by the endwall of a vessel 105, following which the lifting unit 104 submerges themould unit into the vessel, as illustrated by the arrows 115, fordelivering it on to a conveyor movable in the longitudinal direction ofthe vessel and which advances the mould unit through the vessel 105, asshown by the arrow 116. The vessel contains coolant, such as NaCl-brineat a temperature of approximately -18° C. and a freezing of the outerlayer of the fish will therefore be effected in the vessel. Theadvancing rate through the vessel is set so that the fish is freezed toa depth ensuring that the fish preserves its frozen shape, even whenremoved from the mould 102. At the outlet end of the vessel the mouldunit is seized by a transfer unit 106 lifting the mould unit from thevessel (shown by the arrow 117) and displacing it laterally (shown bythe arrow 118) for delivery into a reversing device 107 which extendsparallel to the vessel 105 and returns the mould unit (arrow 119) to aposition opposite the lifting unit 104 simultaneously with turning themould unit 101 upside down so that the inlet opening of each mould facesdownwards. The mould unit 101 is now in an emptying station 108 at whichthe moulds are heated by means of heat radiation or by hot waterflushing so that the fish slips the mould and drops down on to aconveyor 110 which over part of its length is placed in a cooling vessel111 and extends parallel to the reversing device 107. The cooling vessel111 is also filled with coolant, such a brine, and the conveyor 110passes the fish submerged in the coolant through the cooling vessel 111to be picked up and delivered at the end of the vessel, as shown byarrow 122. The fish is frozen in the cooling vessel 111 to such a degreethat it may afterwards be stored straightaway in a cold storage.

A tilting device 109 ensures that the emptied mould unit is inverted anddelivered vis-a-vis the end of the vessel 111 in a transfer unit 112displacing the mould unit laterally to be positioned vis-a-vis thecontainer 103 for refilling the moulds.

The apparatus is distinguished by being extremely compact and simple tooperate so that only a small number of workers are required to freeze alarge quantity of fish in such a shape that in the following processingin land the fish may be positioned as described above.

We claim:
 1. A method of processing roundfish, which have an individualweight as caught from 0.3 to 10 kilos and each has a body with avertebral column (Columna Vertebralis) and a vertical plane of symmetry,into portion packed frozen pieces of fish meat, which roundfish aftercatch and ventral cleaning have been frozen onboard a fishing boat andbeen transported to factory in frozen condition, comprising the stepsof:positioning said roundfish with positioning means that allow thefrozen fish body to be positioned with its vertical plane of symmetryaligned with a cutting means, cutting said roundfish in said frozencondition while being held in said aligned position by fixing means inat least two frozen pieces by at least one longitudinal splitting cutfollowing said vertical plane of symmetry of said frozen fish body, sothat at least the main portion of said vertebral column is removed fromsaid frozen fish meat by said cut, searching said frozen pieces forpossible bone remains and other unwanted impurities which subsequently,at least in part are removed from said frozen fish meat, and packingsaid frozen pieces as portions and then being freeze stored.
 2. A methodas claimed in claim 1, wherein said vertebral column includes spinouspegs and vertebra segments, said longitudinal splitting cut is effectedso that said spinous pegs are cut away from the fish meat buttransversely outer segments of said vertebra segments are left as boneremains in said frozen fish meat, and said bone remains are localized inthe frozen fish meat and removed therefrom.
 3. A method as claimed inclaim 1, wherein said positioning means are at least two plane areasfreeze shaped and placed on the exteriors of the fish and extendingalong a substantial part of the length of the fish.
 4. A method asclaimed in claim 3, wherein said two plane areas are positioned oppositeeach other on either side of said fish body.
 5. A method as claimed inclaim 3, wherein said two plane areas are provided on said fish body byplacing the freshly caught and ventrally cleaned fish body in a mould,which holds said body in mainly straight shape with said two plane areason the exterior of said body, and by keeping said body in said moulduntil at least an outer layer of said body is frozen.
 6. A method asclaimed in claim 1, wherein said positioning means are provided byraising at least two fins on said fish body and by freezing said raisedfins.
 7. A method as claimed in claim 6, wherein said raised, frozenfins are provided on said fish body by suspending said caught andventrally cleaned fish body at its tail, by raising said fins andflushing said fish body with coolant until said raised fins and at leastan outer layer of said fish body are frozen, and by subjecting said fishbody to further freezing while maintaining the shape obtained duringsaid suspending.
 8. A method as claimed in claim 6, wherein said frozenfish body is aligned with said cutting means by inserting said frozen,raised fins into slots in guides arranged at said cutting means.
 9. Amethod as claimed in claim 1, wherein said positioning means areprovided by cutting away at least two fins of said fish body, so thatthe fin rays in the fish meat occur in the cut, and said frozen fishbody is aligned with said cutting means by detecting the positions ofsaid fin rays, by determining said vertical plane of symmetry form saidpositions of said fin rays, and by placing said vertical plane inalignment with said cutting means.
 10. A method as claimed in claim 1,herein said roundfish are individually frozen onboard said fishing boatin mainly straight shape.
 11. A method as claimed in claim 1, whereinsaid fixing means are frozen onto the exterior of said frozen fish body.12. A method as claimed in claim 11, wherein said fixing means arewetted and subsequently brought into contact with the exterior of saidfrozen fish body and fixed to the latter by freezing.
 13. A method asclaimed in claim 12, wherein said fixing means freeze-bonded to theexterior of said frozen fish body are the sole fixing means in contactwith said fish body during splitting of said body by said longitudinalsplitting cut.
 14. A method as claimed in claim 1, wherein both saidsearch for possible bone remains and other unwanted impurities in saidfrozen pieces and said removal of said unwanted impurities from saidfish meat are effected automatically.
 15. A fish processing apparatusfor roundfish which have an individual weight as caught from 0.3 to 10kilos and each has a body with a vertebral column (Columna Vertebralis)and a vertical plane of symmetry, which roundfish after catch andventral cleaning have been frozen onboard a fishing boat and beentransported to factory in frozen condition, wherein said apparatuscomprises a plurality of consecutive stations, including(a) a firststation for infeed of the frozen fish, at which said fish body ispositioned with its vertical plane of symmetry in a predeterminedposition with respect to a holder device having fixing means, and atwhich said frozen fish body is held by said fixing means, said holderdevice being movable as a unit through said consecutive stations, (b) asecond station at which said vertical plane of symmetry is positioned inparallel with a cutting direction of a cutting device, and at which saidcutting device effects at least one cut longitudinally through saidfrozen fish body mainly in parallel with said vertical plane, therebycutting away th major portion of said vertebral column and splittingsaid frozen body in two halves, (c) a third station at which said twofish halves are turned with the cuts facing upward, (d) a fourth stationat which a detector, having a video camera, localizes impurities in thefish meat and records their positioning, (e) a fifth station at whichunwanted impurities are removed by means of a tool, the movement ofwhich is controlled by a control unit which from the detector hasreceived information about the positioning of the recorded impurities,(f) a sixth station at which said cleaned fish halves are released fromsaid holder device, and (g) a seventh station at which said holderdevice is cleaned and prepared for receiving a new, frozen fish body.16. A fish processing apparatus as claimed in claim 15, wherein saidfirst station includes a positioning device for frozen fish bodies withraised, frozen fins having a certain height, which device has a lowerpart and an upper part each with a longitudinal slot guide positionedopposite each other, said slot guides having a length at least of thesame size as said frozen fish body and a depth larger than said heightof said raised fins, said upper part being movable in relation to saidlower part in such a manner that said slot guides in said two partsremain substantially in a common plane.
 17. A fish processing apparatusas claimed in claim 16, wherein said lower part and said slot thereinare considerably longer than said upper part, each of said slot guidesin said lower and upper parts continues into a wedge-shaped infeedopening at one end of said slot guide, and said underside of said upperpart is bevelled at said one end of said slot guide.
 18. A fishprocessing apparatus as claimed in claim 15, wherein said fixing meansof said holder device are lockable in abutment on the exterior of saidfrozen fish body, and said fixing means each include a fluid absorbingand flexible material determined to abut said exterior of said frozenfish body.
 19. A fish processing apparatus as claimed in claim 18,wherein said fluid absorbing and flexible material is of a poroussynthetic material selected from a group including nylon fiber material,foam rubber and polyurethane foam.
 20. A fish processing apparatus asclaimed in claim 18, wherein said holder device has two holders eachcarrying a number of fixing means distributed over a lengthcorresponding to the length of said frozen fish body, which holders aresituated on either side of a fish positioning device and are mountedswingable between a position in which said flexible material can abutthe sides of a frozen fish disposed in said positioning device, and aposition in which the surface of said flexible material determined toabut the fish body faces upwards.
 21. A fish processing apparatus asclaimed in claim 20, wherein said holders are swingable through an angleof 90°.
 22. A fish holding mould for freeze-shaping roundish which havean individual weight as caught from 0.3 to 10 kilos and each has a bodywith a vertebral column (Columna Vertebralis) and a vertical plane ofsymmetry, which roundfish after catch and ventral cleaning onboard thefishing boat is placed in and shaped by said mould and frozen, whereinsaid mould has at least two planar longitudinal lateral faces of alength corresponding to a substantial part of the length of said fishbody, said faces each having two ends and a width which decreases fromtheir one end to the other, said faces having a mutual positioning sothat an internal clearance of said mould in a direction transversely tosaid planar lateral faces is smaller than the anatomical width in thesame direction of said fish inserted in said mould.